|Area||4.88 sq mi (13 km2)|
|- land||4.66 sq mi (12 km2)|
|- water||0.22 sq mi (1 km2)|
|Density||118.3 / km2 (306 / sq mi)|
|- summer (DST)||CDT (UTC-5)|
|Wikimedia Commons: Hartford, Illinois|
Hartford is a village in Madison County, Illinois, United States, near the mouth of the Missouri River. The population was 1,429 at the 2010 census. Lewis and Clark spent the winter of 1803-1804 here, near what has been designated the Lewis and Clark State Historic Site.
Hartford is located at (38.824498, -90.092509).
The village is located approximately 15 miles (24 km) north of downtown St. Louis, Missouri, on the Mississippi River. The confluence of the Missouri and Mississippi rivers is just south of the village limits, while the confluence of the Illinois and Mississippi rivers is approximately 22 miles (35 km) upstream.
According to the 2010 census, the village has a total area of 4.88 square miles (12.6 km2), of which 4.66 square miles (12.1 km2) (or 95.49%) is land and 0.22 square miles (0.57 km2) (or 4.51%) is water.
As of the census of 2000, there were 1,545 people, 650 households, and 434 families residing in the village. The population density was 396.4 people per square mile (153.0/km²). There were 710 housing units at an average density of 182.1 per square mile (70.3/km²). The racial makeup of the village was 98.45% White, 0.13% African American, 0.19% Native American, 0.32% Asian, 0.06% Pacific Islander, 0.32% from other races, and 0.52% from two or more races. Hispanic or Latino of any race were 0.71% of the population.
There were 650 households out of which 27.8% had children under the age of 18 living with them, 52.9% were married couples living together, 11.1% had a female householder with no husband present, and 33.1% were non-families. 28.5% of all households were made up of individuals and 13.8% had someone living alone who was 65 years of age or older. The average household size was 2.38 and the average family size was 2.89.
In the village the population was spread out with 23.3% under the age of 18, 7.5% from 18 to 24, 28.9% from 25 to 44, 23.6% from 45 to 64, and 16.8% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 101.4 males. For every 100 females age 18 and over, there were 94.6 males.
The median income for a household in the village was $33,828, and the median income for a family was $40,652. Males had a median income of $31,694 versus $20,156 for females. The per capita income for the village was $16,160. About 10.3% of families and 13.0% of the population were below the poverty line, including 20.8% of those under age 18 and 4.6% of those age 65 or over.
 Underground gas plume
An estimated 4 million gallons of gasoline have seeped into the ground under Hartford. The area has numerous refineries that have occupied the area for many years. The village filed suit on July 21, 2008, against numerous parties over the underground gas plume.
 Chemetco, Inc
The former copper smelter, Chemetco, operated here for around 30 years ending in 2001. The corporation was found guilty of Clean Water Act offenses after its sustained pollution of Long Lake, a tributary of the Mississippi River, over a ten-year period. This only ended after the detection by EPA inspectors of a secret hazardous waste pipe in September 1996. This site is not technically located within the village limits of Hartford, but south of town, near the community of Mitchell.
- "Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data (DP-1): Hartford village, Illinois". U.S. Census Bureau, American Factfinder. Retrieved January 23, 2012.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "2010 Census U.S. Gazetteer Files for Places – Illinois". United States Census. Retrieved 2012-10-13.
- "Geographic Identifiers: 2010 Demographic Profile Data (G001): Hartford village, Illinois". U.S. Census Bureau, American Factfinder. Retrieved January 23, 2012.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- http://www.thetelegraph.com/news/suit_16407___article.html/village_claims.html Local Newspaper article
- "Chemetco: One polluter, three perspectives" - Original case study of the sustained criminal pollution of Long Lake by Chemetco